A surge of new coronavirus cases in the U.S. is sending people back to stores to stockpile again, leaving shelves bare and forcing retailers to put limits on purchases.

By Joseph Pisani, Anne D'Innocenzio, Associated Press

Many Americans have encountered long lines and empty shelves at grocery stores recently. But the problem is not one of supply; rather, stores say that most shortages are temporary and due strictly to an unprecedented surge in buying, as panicked…